Embodiments relate to a zoom lens and an imaging apparatus that are used for subminiature cameras, digital video cameras, mobile phones, Personal Digital Assistants (PDAs), and the like.
As the development and use of optical imaging devices, such as digital cameras and digital camcorders using a solid-state image pickup device such as a charge coupled device (CCD) or complementary metal-oxide semiconductor (CMOS), have increased considerably, a zoom lens having high performance and a miniaturized and light-weight structure is in demand.
With regard to optical systems including a solid-state image pickup device, market demand is increasing for a wide angle and high resolution lens, and accordingly, a bright lens having a small F-number and a wide angle has been proposed. In addition, a high-performance optical system capable of hand shake correction has been proposed to be used together with a bright lens having a small F-number.
In many cases, optical systems have only one of a wide angle function and a high magnification function, and a bright lens having a small F-number for fixed-focus optical systems. The bright lens having a small F-number has a large size and is heavy and expensive due to its complicated optical structure. In addition, with hand shake correction included in a bright lens having a small F-number also has a large size and is heavy, and accordingly, a control device and a mechanical device used in such a hand shake correction optical system also has a large size.
For example, a wide-angle and bright zoom lens typically consists of five lens groups, and since each lens group individually moves during zooming, the mechanical structure of the wide-angle and bright zoom lens is complicated and it is also large.
In another example, a zoom lens may consist of four lens groups having positive, negative, positive, and positive refractive powers, respectively, and in this case, although an F-number of about 1.8 is realized, the size of a third lens group should be large to realize a slightly brighter large aperture. Accordingly, a control device and a mechanical device for hand shake correction are also large, and thus, the entire lens barrel of the zoom lens must be large as well. In addition, due to the large aperture, it is difficult to control the chromatic aberration of the zoom lens.